Cannonical map to factor domains

(coerce 'x (get-factor-ring R (make-ideal R (expt x 2)))) errors on SBCL. It seems to be getting passed a nil where it expects a fixnum.

Here's my stacktrace

`Value of NIL in
(LET #1=(WEYLI::A-TEMP WEYLI::B-TEMP)
(DECLARE (FIXNUM WEYLI::A-TEMP WEYLI::B-TEMP)
(OPTIMIZE (SAFETY 0)))
(COND
((COMMON-LISP:> (SETQ WEYLI::A-TEMP (SVREF WEYLI::A 1))
(SETQ WEYLI::B-TEMP (SVREF WEYLI::B 1)))
T)
((COMMON-LISP:< . #1#) NIL)))

is
NIL,
not a
FIXNUM.
[Condition of type SIMPLE-TYPE-ERROR]

Restarts:
0: [RETRY] Retry SLIME REPL evaluation request.
1: [*ABORT] Return to SLIME's top level.
2: [ABORT] abort thread (#<THREAD "repl-thread" RUNNING {10038A8033}>)

Backtrace:
0: (SB-C::%COMPILE-TIME-TYPE-ERROR (NIL) FIXNUM # (NIL) "(LET #1=(WEYLI::A-TEMP WEYLI::B-TEMP) ..)
1: (COMPARE<1>-1-NIL-NIL # #)
2: (WEYLI::GTERMS-DIFFERENCE #<FUNCTION COMPARE<1>-1-NIL-NIL> # #)
3: ((LAMBDA NIL :IN WEYLI::DIFFERENCE))
4: ((:METHOD WEYLI::%BIND-DYNAMIC-DOMAIN-CONTEXT (WEYLI::DOMAIN T)) R[x] #<CLOSURE (LAMBDA NIL :IN WEYLI::DIFFERENCE) {100529125B}>) [fast-method]
5: ((:METHOD WEYLI::%BIND-DYNAMIC-DOMAIN-CONTEXT (WEYLI::HAS-COEFFICIENT-DOMAIN T)) R[x] #<CLOSURE (LAMBDA NIL :IN WEYLI::DIFFERENCE) {100529125B}>) [fast-method]
6: ((:METHOD WEYLI::BINARY= (WEYLI::EPOLYNOMIAL WEYLI::EPOLYNOMIAL)) x^2 x^2) [fast-method]
7: (SB-KERNEL:%MEMBER-TEST # # #)
8: ((:METHOD WEYLI::BINARY= (WEYLI::IDEAL WEYLI::IDEAL)) #Id( x^2) #Id( x^2)) [fast-method]
9: (FIND NIL (#1=#2=R[#3=x#4=]/#Id( #3#^2) #1# C #2#[#3#, y#4# #2# #<Domain: GFP> ...) :TEST #<CLOSURE (LAMBDA (WEYLI::A WEYLI::B) :IN WEYLI::ADD-DOMAIN-INTERNAL) {100529113B}>)
10: (WEYLI::ADD-DOMAIN-INTERNAL #<CLOSURE (LAMBDA (WEYLI::D) :IN GET-FACTOR-RING) {10052910FB}> #<CLOSURE (LAMBDA NIL :IN GET-FACTOR-RING) {100529111B}>)
11: (SB-INT:SIMPLE-EVAL-IN-LEXENV (GET-FACTOR-RING R (MAKE-IDEAL R (EXPT X 2))) #)
12: (SB-INT:SIMPLE-EVAL-IN-LEXENV (COERCE (QUOTE X) (GET-FACTOR-RING R (MAKE-IDEAL R #))) #)
13: (EVAL (COERCE (QUOTE X) (GET-FACTOR-RING R (MAKE-IDEAL R #))))
--more--`

[ThomasHermann]

Thanks for the feedback, sorry for the late reply.

Tested this in CCL, SBCL, and LispWorks and obtained an unbound variable error for R. It's been a long while since I worked through this package, so if you could provide more info, that would help.

Thanks again,

Tom